NAME

SYNOPSIS

DESCRIPTION

The file
/usr/sbin/nfsidmap
is used by the NFS idmapper to translate user and group ids into names, and to
translate user and group names into ids. Idmapper uses request-key to perform
the upcall and cache the result.
/usr/sbin/nfsidmap
is called by /sbin/request-key, and will perform the translation and
initialize a key with the resulting information.

nfsidmap
can also used to clear the keyring of all the keys or
revoke one particular key.
This is useful when the id mappings have failed to due
to a lookup error resulting in all the cached uids/gids to be set
to the user id nobody.

OPTIONS

-c

Clear the keyring of all the keys.

-g user

Revoke the gid key of the given user.

-r user

Revoke both the uid and gid key of the given user.

-t timeout

Set the expiration timer, in seconds, on the key.
The default is 600 seconds (10 mins).

-u user

Revoke the uid key of the given user.

-v

Increases the verbosity of the output to syslog
(can be specified multiple times).

CONFIGURING

The file
/etc/request-key.conf
will need to be modified so
/sbin/request-key
can properly direct the upcall. The following line should be added before a call
to keyctl negate:

createid_resolver**/usr/sbin/nfsidmap -t 600 %k %d

This will direct all id_resolver requests to the program
/usr/sbin/nfsidmap.
The
-t 600
defines how many seconds into the future the key will
expire. This is an optional parameter for
/usr/sbin/nfsidmap
and will default to 600 seconds when not specified.

The idmapper system uses four key descriptions:

uid: Find the UID for the given user

gid: Find the GID for the given group

user: Find the user name for the given UID

group: Find the group name for the given GID

You can choose to handle any of these individually, rather than using the
generic upcall program. If you would like to use your own program for a uid
lookup then you would edit your request-key.conf so it looks similar to this:

createid_resolveruid:**/some/other/program %k %d

createid_resolver**/usr/sbin/nfsidmap %k %d

Notice that the new line was added above the line for the generic program.
request-key will find the first matching line and run the corresponding program.
In this case, /some/other/program will handle all uid lookups, and
/usr/sbin/nfsidmap will handle gid, user, and group lookups.